<template>
	<view >
	<button @tap="createCanvas">签名</button>
	<view class="signature" v-show="showCanvas">
		<canvas class="mycanvas" canvas-id="mycanvas" @touchstart="touchstart" @touchmove="touchmove" @touchend="touchend"></canvas>
		<view class="footer">
			<view class="left" @click="finish">保存</view>
			<view class="right" @click="clear">清除</view>
			<view class="close" @click="close">关闭</view>
		</view>
	</view>
		
	</view>
</template>

<script>
		var x = 20;
		var y =20;
	export default {
		data() {
			return {
				showCanvas:false,
				ctx:'',         //绘图图像
				points:[],       //路径点集合 
				signature:''
			}
		},
		methods: {
			//关闭并清空画布
			close:function(){
				this.showCanvas = false;
				this.clear();
			},
			//创建并显示画布
			createCanvas:function(){
				this.showCanvas = true;
				
				this.ctx = uni.createCanvasContext("mycanvas",this);   //创建绘图对象
				
				//设置画笔样式
				this.ctx.lineWidth = 4;
				this.ctx.lineCap = "round"
				this.ctx.lineJoin = "round"
			},
			//触摸开始，获取到起点
			touchstart:function(e){
				let startX = e.changedTouches[0].x;
				let startY = e.changedTouches[0].y;
				let startPoint = {X:startX,Y:startY};
				this.points.push(startPoint);
				//每次触摸开始，开启新的路径
				this.ctx.beginPath();
			},
			
			//触摸移动，获取到路径点
			touchmove:function(e){
				let moveX = e.changedTouches[0].x;
				let moveY = e.changedTouches[0].y;
				let movePoint = {X:moveX,Y:moveY};
				this.points.push(movePoint);       //存点
				let len = this.points.length;
				if(len>=2){
					this.draw();                   //绘制路径
				}
				
			},
			
			// 触摸结束，将未绘制的点清空防止对后续路径产生干扰
			touchend:function(){                   
				this.points=[];
			},
			
			/* ***********************************************
			#   绘制笔迹
			#	1.为保证笔迹实时显示，必须在移动的同时绘制笔迹
			#	2.为保证笔迹连续，每次从路径集合中区两个点作为起点（moveTo）和终点(lineTo)
			#	3.将上一次的终点作为下一次绘制的起点（即清除第一个点）
			************************************************ */
			draw: function() {
				let point1 = this.points[0]
				let point2 = this.points[1]
				this.points.shift()
				this.ctx.moveTo(point1.X, point1.Y)
				this.ctx.lineTo(point2.X, point2.Y)
				this.ctx.stroke()
				this.ctx.draw(true)
			},
			
			//清空画布
			clear:function(){
				let that = this;
				uni.getSystemInfo({
					success: function(res) {
						let canvasw = res.windowWidth;
						let canvash = res.windowHeight;
						that.ctx.clearRect(0, 0, canvasw, canvash);
						that.ctx.draw(true);
					},
				})
			},
			//完成绘画并保存到本地
			finish:function(){
				let that = this;
				uni.canvasToTempFilePath({
				  canvasId: 'mycanvas',
				  success: function(res) {
					  console.log(res.tempFilePath)
						
					//上传到服务器
					// that.api.uploadFile({
					// 	url: 'user/upload/one',
					// 	filePath: res.tempFilePath,
					// 	name: 'file',
					// 	success: (uploadFileRes) => {
					// 		console.log(uploadFileRes)
					// 		that.signature = uploadFileRes.data.url;
					// 		that.clear();
					// 		that.showCanvas = false;
					// 	}
					// })
					//保存到本地
					/* 
					
					let path = res.tempFilePath;
					uni.saveImageToPhotosAlbum({
						filePath:path,
					}) */
				  } 
				})
			},
		}
	}

</script>

<style>
	
		.signature {position: fixed;top: 10px;left: 2%;z-index: 999;width:96%;}
		page{
			background: #fff;
		}
		.container {
			padding: 20rpx 0 120rpx 0;
			box-sizing: border-box;
		}
		.title{
			height:50upx;
			line-height: 50upx;
			font-size: 16px;
		}
		.mycanvas{
			width: 100%;
			height: calc(100vh - 200upx);
			background-color: #ECECEC;
		}
		.footer{
			font-size: 14px;
			height: 150upx;
			display: flex;
			justify-content: space-around;
			align-items: center;
		}
		.left,.right,.close{
			line-height: 100upx;
			height: 100upx;
			width: 220upx;
			text-align: center;
			font-weight: bold;
			color: white;
			border-radius: 5upx;
		}
		.left{
			background: #007AFF;
		}
		.right{
			background:orange;
		}
		.close {
			background:#A3A3A3;
		}

</style>
